As the majority of the public will still most likely treat the Ads with skepticism and scroll down (now further) until they see the "real" results in the Organic section, this is all about Google creating MORE competition amongst advertisers for LESS space, and thus with Supply & Demand, the price of everybody's Adwords will go up.

One of the best hidden gems in your superb article and research (nice graphics too!), Andrea was the fact that only 1% or less of users prefer the current trend of vertical "Parallax" scrolling to deliver content. I thought I was the only one on the planet that was driven nuts by it. Thank you for putting my mind at ease. It's the scourge of the current drive to "mobile up" (make Responsive) all content at the expense of the majority who still use Laptop & Desktops to access content. It's like the rest of us have been forgotten in the relentless drive for uber-Responsiveness whilst losing the degree of control that traditional sites have.

I was also intrigued by the results of the 300 words' optimal length of content. Our olde English teachers back in the school days would be rolling in their graves at "half at essay" (600-800 words used to be the norm). I would agree with other comments though that even though 300 words is certainly aimed at the quick dip the majority now want to consume content, at the expense of it not making a dent on Google positioning for the majority of sites.